Steel Glossary

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Alloy steel An iron based mixture is considered to be an alloysteel when it contains more than 1.65 wt% of Manganese (Mn), 0.5 wt%of Silicon (Si), 0.6 wt% of Copper (Cu) and/or other minimum quantities of alloying elements such as Chromium (Cr), Nickel (Ni), Molybdenum (Mo), or Tungsten (W). Through combining different quantities and types of alloying elements, a wide variety of distinct properties can be produced in steel.
Arcing Arcing is the formation of an el ectric arc between the graphite electrode(s) of the furnace and the conductive content of the furnace such as steel scrap or molten steel. The arcing process that takes place in an electric arc furnace (EAF) is similar in principle to that of electric arc welding, except that the current is much higher in the EAF.
Bars Long products that are rolled from billets. The two common categories are merchant bar and reinforcement bar (rebar). Merchant bars include rounds, flats, angles, squares and channels. These products are often further processed to produce a wide variety of products such as furniture, stair railing, farm equipment, etc. Reinforcement bars are used predominantly for reinforcing concrete structure such as highways, bridges and buildings. At our plant in Singapore, we only produce rounds ranging from 10mm to 32mm and reinforcement bars from 10mm to 50mm.
Billets Semi-finished steel forms that are used for the production of long products. Billets generally have square cross-sectional areas compared to blooms and slabs, which generally have larger aspect ratios. Billets can be produced from a caster or rolled from a bloom. NatSteel Holdings produces most of the billets it consumes in-house with continuous casting technology. Only a small proportion of billets (special grades) are purchased from international steel manufacturers. In-house production of billets provides flexibility in terms of material properties and production yield optimisation.
Blast furnace A towering cylinder lined with heat resistant (refractory) bricks, used by integrated steel works to smelt iron from iron ore. Its name is derived from the blast of hot air and gases forced up through the iron ore, coke and lime stone loaded in the furnace. Inside the blast furnace, the iron ore is chemically reduced to iron and physically converted (melted) to liquid iron. This is the iron-making process.NatSteel Holdings' steel factory produces steel from scrap and does not use blast furnaces.
Carbon steel A type of steel whose properties are determined primarily by the percentage of carbon present. Minor elements are present in minute quantities below the amounts found in alloy steels.
Casting The process of pouring molten metal into a mould such that upon cooling, the solidified metal retains the shape of the mould.
Continuous casting Continuous forming of semi-finished steel products such as billets, blooms and slabs. Molten metal is poured continuously from a buffer refractory container known as a tundish into a water-cooled copper mould of the caster. Molten steel solidifies when it contacts the water-cooled mould to form an external shell of sufficient strength that will hold the remaining molten steel in its core. A spray of water assists the extraction of heat from this partially solidified steel strand.At the bottom of the steel caster, the steel strand is torch-cut into required lengths. Continuous casters can be used for producing slabs, blooms and billets, and are usually able to cast a few strands of steel simultaneously. NatSteel Holdings uses a five-strand continuous caster that produces billets with cross-sectional areas of up 164mm².
Charging The feeding of a single load of raw materials into the furnace.
Cut-and-bend It is one of the most important operations in the construction of a reinforced concrete product. It involves cutting and bending the reinforcement bar into the correct size and shape as specified in structural drawings so as to allow trouble-free placement of the steel in the structural member at the construction site.Cutting and bending can be done on the construction site itself or at a cut-and-bend shop. The former often results in inappropriate dimensioning and inaccurate bending. The latter provides a controlled and organised environment where skilled operators produce consistently good quality products.With prefabricated cut-and-bend rebars, construction sites reduce material wastage and fixing time significantly.NatSteel Holdings is considered a pioneer of cut-and-bend services for Singapore's construction industry and operates one of the world's largest single cut-and-bend facility.
Electric arc furnace A steelmaking furnace which predominantly uses scrap as an iron source. The furnace houses either one or three graphite electrodes from which an electric arc can be generated to provide heat to melt the steel scrap.Electricity can be applied either as direct current (DC), where only one electrode is required, or alternate current (AC), where three electrodes are required. These two types of furnaces are respectively known as DC furnace and AC furnace.Our factory operates a DC Finger Shaft Furnace with an 80-tonne capacity per heat.
Flat products Steel products with typical aspect ratios of greater than 100. Examples are sheets, strips and plates used in automotives, shipbuilding and electronic white goods.
Ladle A refractory brick-lined steel vessel that is usually shaped like a bucket. It is used for transferring molten steel between processes in a steel plant. For instance, a ladle can be used to transfer molten steel from the electric arc furnace to the ladle furnace for secondary refinement and then to transfer the refined molten steel to the continuous caster.
Long products Refers to steel products such as bars, rods and structural constructions that are "long" rather than "flat". These are used for building projects.The reinforcement bars and wire rods produced at NatSteel Holdings are available in various grades for different applications.
Mesh Another name for Welded Wire Mesh
mt Metric tonne —  1 tonne is equivalent to 1,000 kg
Precast concrete (PC) A technology which involves casting building units (e.g. toilets, rooms, balconies, etc) away from the installation site, so that casting and on-site work can take place simultaneously and reduce project time
PC wires Wires (mild or high tensile steel round bars with diameters ranging from 5mm to 40mm) that are used in precast concrete
Pig iron Refers to melted iron (containing carbon above 1.5%) produced in a blast furnace. Molten iron is poured through a trench before flowing into shallow earthen moulds arranged along the side of the trench. As this resembles newborn pigs suckling at their mother’s side, the trench became known as the “sow” and the moulds as “pigs”.At NatSteel Holdings, pig iron is sometimes used as an alternative iron source to produce special grade steel which otherwise cannot be made from steel scrap which contains a higher proportion of impurities.
Radiation Spontaneous disintegration of radioactive elements (e.g. Co-60, Ra-226, Cs-137) into other elements, accompanied by the radiation of high energy and harmful y-rays.If a radioactive material is melted in the electric arc furnance, Co-60 is the most likely radioactive element to be alloyed with the steel due to its close melting point, while Cs-137 ends up in the dust and Ra-226 in the slag.NatSteel Holdings screens all incoming scrap via a radiation detection system before it is charged into the furnace. Steel samples from the furnace, billets and our steel products are also tested at the lab with a radiation measurement unit. NatSteel Holdings adopts a stringent limit of 0.1Bq/g (the International Atomic Energy Agency recommends 0.3Bq/g) of total radioactivity in all of its products.
Rebars Another name for reinforcement bars
Reinforcement bars Steel rods used to reinforce or strengthen thick concrete structures.
Rods Another name for wire rods
Refractories Heat resistant material used for lining the furnace and ladle to provide heat insulation and protect the equipment that is usually made of steel. Refractory material is available in either brick form or paste form.
Rolling The reduction in diameter of semi-finished steel products such as billets, blooms and slabs by squeezing the products between horizontal or vertical pairs of rollers.The distinction between cold- and hot-rolling is the temperature at which rolling is carried out. Cold-rolling often takes place at room temperature while the hot rolling temperature range varies from metal to metal. The two processes impart different properties to the products.NatSteel Holdings uses cross-country, single- and two-strand tandem bar mills.
Slag A by-product of the iron and steelmaking process comprising largely of limestone. During steelmaking, slag, which has a lower density than molten steel, floats above the molten steel and acts as a scavenger for undesirable elements in the steel.Once cooled and solidified, slag can be used in soil mixtures, road stones and cement.
Steel scrap Scrap is the collective name for ferrous components that have reached the end of their useful life cycle, for instance, unserviceable machine parts, steel parts of ships, bridge structures, old car parts as well as reverted ferrous materials from steelmaking.
Strands Cables produced by taking relevant diameters of wires braided together in a bundle, and can be used in precast concrete or wall anchors, lifting strands, etc.
Tensile strength The greatest longitudinal stress a material can bear without tearing apart
Tapping The running off of molten steel from the tap hole in a furnace or vessel
Tundish A shallow, refractory-lined basin that is placed under a ladle and above a continuous caster. A tundish acts as a buffer by receiving the liquid steel from the ladle prior to entering the cast, allowing the operator to regulate the flow of metal into the mould.
Welded wire mesh Fabric reinforcement that is made up mainly of high-strength wires that are welded at intersections. The use of mesh as reinforcement significantly reduces cutting and fixing time at construction sites. It also enables the simplification of the engineering design and drawing.NatSteel Holdings produces mesh and prefabricated steel structures, which cut wastage, reduce land and labour costs, and are delivered just-in-time to sites.
Wire rods Round steel bars of diameters ranging from 5.5mm to 16mm that are hot-rolled from billets and coiled at the end of the rolling process. Rods are semi-finished products used as feed for wire mills or raw material for bolts and nuts. Some wire rods are also sold to building contractors and other steel processing plants.NatSteel Holdings produces rods of diameters ranging from 5.5mm to 16mm. Examples of the grades of rods produced are:
• Low Carbon Quality
• Welding Electrode Quality
• High Carbon Quality
• Cold Heading Quality (Rimmed, Aluminium-killed)

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